Magnetic shunt switches and the like



June 2, 1970 I L. N. LEA

MAGNETIC SHUNT SWITCHES AND THE LIKE Filed Jan. 5. 1969 FIG.2

lfiv k- IN VEN 1"( R, Lawrence N.Le0,,

\ ATTORNEY.

United States Patent 3,516,036 MAGNETIC SHUNT SWITCHES AND THE LIKE Lawrence N. Lea, 1683 University Ave., New York, N.Y. 10453 Filed Jan. 3, 1969, Ser. No. 788,794 Int. Cl. H01h 3/16 US. Cl. 335207 Claims ABSTRACT OF THE DISCLOSURE A magnetic switch construction for protecting a door in a burglar alarm system, which permits one opening of the door without actuating the alarm circuit, includes an auxialiary bar magnet to be moved from a normal rest position on the jamb to a second position whereat the armature of the switch on the jamb is within the influence of the auxiliary magnet, and alsowhereat the main bar magnet on the door which acts on said armature while the door is closed, to hold the switch in a predetermined condition, subjects the auxiliary magnet to a repelling force biasing it to return to its normal rest position whereat the auxiliary magnet has no effect on the armature. When the auxiliary magnet is brought by hand to said second position and held thereat while the door is being opened, it may then be let go. The switch condition is immobilized until the door is closed again, whereupon the main magnet takes over and repels the auxiliary magnet back to normal rest position.

The present invention relates to shunt switches and the like, for use in burglar alarm systems employing magnetic switches.

The principal object of this invention is to provide a magnetic switch device of novel and improved construction, for use at the door through which the last person in the premises will go out from, after the burglar alarm system has been set in operative condition; such device permitting only one opening of the door per manipulation of the device from inside the premises, without actuating the alarm.

Another object thereof is to provide an attachment to present magnetic switches used at such doors, to attain said principal object.

A further object thereof is to provide an immobilization of switch condition for the required purpose by use of new switch structure having a new mode of operation.

Still a further object of this invention is to provide a novel and improved magnetic switch construction of the character set forth having the aforementioned attributes, and which is simple and reasonable in cost to manufacture, easy to install, and efiicient in carrying out the purposes for which it is designed.

Other objects and advantages will become apparent as this disclosure proceeds.

For one practice of this invention, a main permanent bar magnet is housed in a plastic casing mounted on the face of the door inside the protected premises, so the magnet extends vertically along another plastic casing which is mounted on the jamb and houses a switch including a movable armature. When the door is closed, the magnet will move the armature and hold it in position so that the switch is in closed condition. An auxiliary permanent bar magnet is vertically carried and vertically slidable on the switch-holding casing. Similar poles of said magnets are at their corresponding ends respectively. At the normal rest position of the auxiliary magnet, nearly all of it is below the casings, and it neither effects nor is effected by the permanent magnet or the said armature. However, upon manually lifting the auxiliary magnet, it acts to attract the armature and be held by it, and becomes subject while the door is closed, to be repelled by the main magnet to return to its normal rest position if let free of manual hold.

In the accompanying drawing forming part of this specification, similar characters of reference indicate corresponding parts in all the views.

FIG. 1 is a perspective view of a protective switch device embodying the teachings of this invention, installed on the door structure which will be used for egress of the last person in the premises. This view is largely diagrammatic and not to scale.

FIG. 2 is a view like FIG. 1, showing a manual manipulation preparatory to opening the door.

FIG. 3 is a similar view showing the switch condition immobilized while the door is opened so the last person can leave the premises, without activating the alarm circuit.

FIG. 4 is an enlarged perspective view of the switch part of the device, whose casing is broken away to expose the armature included in such switch.

FIG. 5 is a similar view of the main bar magnet of the device, whose casing is broken away to expose such magnet.

FIG. 6 is a similar view of the auxiliary bar magnet of the device, shown in its normal rest position, whose casing is broken away to expose a cap which holds said auxiliary magnet in assembly.

FIG. 7 is a perspective view of the main bar magnet included in FIG. 5.

FIG. 8 is a perspective view of the switch elements included in FIG. 4.

FIG. 9 is a perspective view of the auxiliary magnet included in FIG. 6.

FIG. 10, is a section taken at line 10-10 in FIG. 1, omitting the plastic casing.

In the drawing, the numeral 15 designates the door from which the last person in the premises is to leave through after the burglar alarm system protecting the premises has been set into operative condition; the switch at said door which is in the protective circuit of said system, being of the magnetically-operated type consisting of a permanent bar magnet 16 on the inside face of the door, which when the door is in closed condition, attracts the movable armature 17 of a switch device, and maintains the switch in a given condition whereby the alarm circuit remains inactive, but upon opening the door, the magnet will move away, and so the armature will return to its normal rest position, whereupon the alarm circuit will be actuated; said switch device being mounted on the jamb 18. The switch may consist of the armature 17 which contacts the element 19 when the door is closed, or of any other construction involving the use of an armature as its operating element. No part of the circuit is shown, since this invention has no concern therewith and such circuits and systems are well known. The use of the magnetic switch thus far described in this paragraph, is also well known, and suffices for the protection of a door which is not to be used for the last person to get out of the premises. It may be noted that the bar magnet 16 is housed in a rectangular casing 20, having oppo- Patented June 2, 1970 sitely extending base lugs 21 adapted to receive screws for mounting same, and that the switch comprising the components 17 and 19, is housed in a similar casing 22; said casings being of plastic. The numerals 17 and 19' are the switch terminals which are connected to the switch parts 17 and 19 respectively.

Also carried on the jamb 18, is an auxiliary bar magnet 23, which is adapted to be manually shiftable from a normal rest position thereon, to asecond position where it is manually held, so it is positioned along the side edge of the armature 17, and alongside the main magnet 16, so that the polarity of corresponding ends of said magnets are the same. It is preferred that the bar magnets shall be vertically positioned and that the armature 17 shall be a cantilever extending along the vertical. The auxiliary magnet 23 may have its own plastic casing 24, which is closed by a saddle 25, for mounting it on the front of the casing 22, or, a single casing, not shown, may serve in place of the separate casings 22 and 24. The entities shown in FIGS. 4 and 5, comprise a well known commercial type of magnetic switch used in the burglar alarm art. In order to give the advantages of the present invention, the entity of FIG. 6 may be manufactured as a separate item, for association therewith as shown. Of course, as an original manufacture, the casings 22 and 24, as mentioned, may be a single structure.

At the normal rest position, the auxiliary magnet 23 is nearly for all of its length, outside its casing 24, but

is maintained in association therewith, because of its cap 23, which comes to rest against the inner seat 26. Said auxiliary magnet is freely slidable, and of course, at its normal rest position, it neither influences, nor is influenced by the main magnet 16 or the armature 17. But at its second position, the mutual attraction of the armature 17 and the auxiliary magnet 23, is sufiicient to immobilize both of them when the door is opened, at which time the main magnet 16 is ineffective against them. However, upon closing the door, the main magnet not only maintains the immobilized position of the armature, but repels the auxiliary magnet with sufficient force to return it to its normal rest position.

In FIG. 1, the door 15 is in closed condition and the auxiliary magnet 23 is in its normal rest position. The main bar magnet 16 has shifted the armature 17 and holds it in contact with the element 19. The switch whose terminals are 17', 19, is in closed condition. The burglar alarm system (not shown) protecting the premises, has been set into operative condition; the said switch at the door 15, being in said systems protective circuit. If the door is opened now, the alarm circuit would be actuated. But it is desired to open the door so the last person in, may leave without sounding the alarm, but that only that one opening of the door, is excused by the system. So to accomplish this, the last person to leave, or one of a group of people who is to leave the premises with him, uses his finger 27 to lift the auxiliary magnet 23 to its mentioned second position where its pole N is opposite pole N of the main magnet 16. He continues to hold the auxiliary magnet in its raised position while he opens the door 15. Thereupon he lets go of the auxiliary magnet, for it will remain raised by the attraction between said auxiliary magnet and the armature, and the armature will remain in its position maintaining the switch closed. This situation is illustrated in FIG. 3. Everyone now leaves the premises through the open door. Then upon closing the door, the main magnet 16 again acts to keep the switch closed as in FIG. 1, and by repulsion, has sent the auxiliary magnet 23 back to its normal rest lowered position as shown in FIG. 1. Now, should the door be opened, the alarm will be actuated. As is well known, this occurs because the main magnet 16 has moved away, so the cantilever spring-biased armature 17 has been relieved of its influence, and will move to a normal rest position in which the switch condition is such that the alarm circuit will be actuated.

It is most practical to mount the device along the vertical as shown in FIG. 1 at the handle edge of the door, and have the auxiliary magnet return by downward movement when repelled by the main magnet to normal rest position, but this is not mandatory for it will work in any direction. However, to mount the device along the horizontal, would position its components along the top edge of the door and its frame, which would make access thereto inconvenient in most instances because it would be out of reach. It is believed readily understood to those versed in the art, without the need of further illustration,

that the auxiliary magnet may hang downward on the jamb 18, or from the casing 22, from a chain, to be set in the required position adjacent and along the armature in casing 22, when needed to accomplish its use. Upon closing the door after its one permitted opening, the auxiliary magnet will be repelled and fall, but being at the end of a chain, is available for its next use. The chain may be on the screw used at the assembly eyelet 31, or engaged by said eyelet at the factory at the mounting of the back cover 32 of said casing 22. In fact, the auxiliary magnet may be an unattached piece kept in a handy place near the door. In such instance, upon use, it would fall to the floor upon the closing of the door after its one permitted opening, to be retrieved when the premises are again opened for use.

This invention is capable of numerous forms and various applications without departing from the essential features herein disclosed. It is therefore intended and desired that the embodiments herein shown and described shall be merely illustrative and not restrictive; reference being had to the following claims to indicate the scope of this invention.

I claim:

1. In a magnetic shunt switch construction for use in a burglar alarm system including a movable member and stationary member for allowing one movement of the movable member without actuating the alarm circuit of said system which has been set in operative condition, the combination of a main permanent bar magnet on a mounting element of non-magnetic material mounted on the movable member, a switch device on a second mounting element of said material mounted on the stationary member; said switch device including a movable armature biased to a normal rest position and adapted to be moved by said main magnet to a second position whereupon the switch device is set in a predetermined condition to hold the alarm circuit inactive; said main magnet and armature being opposite one another when the movable member is adjacent the stationary member, whereupon said armature is moved to its said second position, and an auxiliary permanent bar magnet adapted to be manually placed on the second mounting element, along the main bar magnet and adjacent the armature and there manually held only until the movable member is moved away from the stationary member; said auxiliary magnet maintaining said switch condition while the movable member is away from the stationary member and remain in its set position though freed of the manual hold; said set position of the auxiliary bar magnet being away from the path of movement of the movable member; the poles of said auxiliary magnet being opposite the corresponding poles 3. A magnetic shunt switch construction as defined in References Cited claim 1, wherein the auxiliary magnet is movably mounted UNITED STATES PATENTS v wlthrespcctto the frame' 2,600,581 6/1952 Schenendorf 340 274 X 4. A magnetic shunt switch construction as defined in claim 1, wherein the auxiliary bar magnet is movably 5 BERNARD A. GILHEANY, Primary Examiner mounted on the second mounting element. N. ENVALL, JR Assistant Examiner 5. A magnetic shunt switch construction as defined in claim 4, wherein the auxiliary bar magnet is longitudinally slidably mounted; said magnets being parallel. l1685; 20061.81 

